US8207366B2 - Method for producing alkyl chlorosilanes from the residues of the direct synthesis of alkyl chlorosilanes - Google Patents
Method for producing alkyl chlorosilanes from the residues of the direct synthesis of alkyl chlorosilanes Download PDFInfo
- Publication number
- US8207366B2 US8207366B2 US12/865,664 US86566409A US8207366B2 US 8207366 B2 US8207366 B2 US 8207366B2 US 86566409 A US86566409 A US 86566409A US 8207366 B2 US8207366 B2 US 8207366B2
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- United States
- Prior art keywords
- residues
- direct synthesis
- alkylchlorosilanes
- reactor
- reaction mixture
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic System
- C07F7/02—Silicon compounds
- C07F7/08—Compounds having one or more C—Si linkages
- C07F7/12—Organo silicon halides
- C07F7/121—Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20
- C07F7/128—Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20 by reactions covered by more than one of the groups C07F7/122 - C07F7/127 and of which the starting material is unknown or insufficiently determined
Definitions
- the invention relates to a process for producing alkylchlorosilanes from the residues from the direct synthesis of alkylchlorosilanes via heating by alternating current.
- Oligosilanes make up the main part of the residues, and in particular the disilanes of the general formula R c Cl 6-c Si 2 , in which c is from 0 to 6.
- silane compounds having more than 2 Si—Si bonds can also be present, examples being trisilanes or silamethylenes. In all these formulae, silicon is tetravalent.
- U.S. Pat. No. 2,598,435 describes a process in which methylchloromonosilanes are obtained from residues from the direct synthesis of methylchlorosilanes which comprise methylhalopolysilanes, at temperatures of from 250 to 800° C.
- alkylchlorosilanes are produced from the residues from the direct synthesis of alkylchlorosilanes, which comprise liquid constituents with a boiling point >70° C. and solids, using HCl at from 300 to 800° C. in a tubular reactor with rotatable internals.
- the rotatable internals are needed for scraping to remove caked material produced by carbonization on the reactor walls.
- additives e.g. hydrogen chloride, hydrogen, or catalysts
- the invention thus provides a process for producing alkylchlorosilanes from the residues from the direct synthesis of alkylchlorosilanes, which comprise liquid constituents with a boiling point of at least 70° C. at 1013 hPa and further constituents, including metals and compounds thereof, in which the reaction mixture is heated in a pressurized reactor to a reaction temperature of from 200 to 500° C. via passage of alternating current.
- the process uses residues from the direct synthesis of alkylchlorosilanes to provide useful monosilanes. It is preferable here that relatively high-molecular-weight constituents of the residues are cleaved to give monosilanes.
- the process preferably requires no use of catalysts and no use of further starting materials. Deposits of solids on the reactor walls are very substantially avoided.
- Methylchlorosilanes of the general formula Me a H b SiCl 4-a-b are preferably produced, in which Me is a methyl moiety, a is 1, 2, or 3, and b is 0 or 1.
- the residues from the direct synthesis consist in essence of volatile constituents with a boiling point of at least 70° C., in particular at least 100° C., at 1013 hPa, and metals or compounds of these, in dissolved or finely suspended form.
- the residues comprise metals from the group of Al, Cu, Zn, Sn, Fe, Ti, and/or compounds of these.
- the residues can also comprise further solids, e.g. silicon and carbon black.
- the residue mostly comprises disilanes.
- the residues are introduced batchwise or continuously into a pressurized reactor and heated to the temperature required for reaction via passage of alternating current.
- the reactor is preferably operated at at least 250° C. and with preference at at most 350° C.
- the pressure is preferably at least 20 bar, more preferably at least 30 bar, and preferably at most 100 bar, in particular at most 80 bar.
- the reaction product is preferably condensed, and if appropriate freed from solids, and can be returned to the alkylchlorosilane mixture produced in the direct synthesis process, or else can be separately isolated to give pure substances.
- Me means a methyl moiety
- a high-boiling-point residue from the direct synthesis of methylchlorosilanes was used and according to GC was composed of:
- the high-boiling-point residue was fed in liquid form into an autoclave of volume 0.92 1.
- the reaction mixture was heated to 270° C. via passage of alternating current and kept at this temperature for 180 min.
- the autoclave was cooled to ambient temperature.
- the product mixture was removed and analyzed by GC:
Abstract
High boiling residue from the direct synthesis of alkylchlorosilanes are converted in large part to monosilanes by heating the residue by passage of alternating current in a pressurized reactor.
Description
This application is the U.S. national phase of PCT Appln. No. PCT/EP2009/051771 filed Feb. 16, 2009 which claims priority to German application DE 10 2008 000 410.3 filed Feb. 26, 2008.
1. Field of the Invention
The invention relates to a process for producing alkylchlorosilanes from the residues from the direct synthesis of alkylchlorosilanes via heating by alternating current.
2. Description of the Related Art
When metallic silicon and alkyl chlorides RCl, where R is an alkyl moiety, are used in the direct synthesis of alkylchlorosilanes of the general formula RaHbSiCl4-a-b in which a is 1, 2, 3, or 4 and b is 0, 1, or 2, the by products comprise oligosilanes, carbosilanes, siloxanes, and high-boiling-point cracking products. The residues also comprise solids derived from the direct synthesis process which are very fine and are not retained by cyclones and filters. These solids are composed of silicon, metals, and compounds of these, metal silicides, and carbon black.
Oligosilanes make up the main part of the residues, and in particular the disilanes of the general formula RcCl6-cSi2, in which c is from 0 to 6. However, silane compounds having more than 2 Si—Si bonds can also be present, examples being trisilanes or silamethylenes. In all these formulae, silicon is tetravalent.
U.S. Pat. No. 2,598,435 describes a process in which methylchloromonosilanes are obtained from residues from the direct synthesis of methylchlorosilanes which comprise methylhalopolysilanes, at temperatures of from 250 to 800° C.
A wide variety of specifications, e.g. EP 1505070 and publications cited therein, describe processes in which residues from the direct synthesis of alkylchlorosilanes can be cleaved to give alkylchloromonosilanes, using additions of HCl and/or H2 and sometimes using complex catalyst systems. U.S. Pat. No. 2,681,355 describes a continuous process in which residues from the direct synthesis of methylchlorosilanes are reacted in an externally heated tube with HCl at temperatures of from 400 to 900° C. to form monomeric silanes, without catalysis and by a purely thermal route. Large amounts of by products are formed here, examples being carbosilanes and polymers, and also solids, because of carbonization of the residues on hot reactor walls.
DE 19711693 describes a continuous process in which alkylchlorosilanes are produced from the residues from the direct synthesis of alkylchlorosilanes, which comprise liquid constituents with a boiling point >70° C. and solids, using HCl at from 300 to 800° C. in a tubular reactor with rotatable internals. The rotatable internals are needed for scraping to remove caked material produced by carbonization on the reactor walls.
It was an object to provide a process which can produce alkylchlorosilanes from the residues from the direct synthesis of alkylchlorosilanes and which provides a high yield of alkylchlorosilanes purely via thermal treatment and without further additives, e.g. hydrogen chloride, hydrogen, or catalysts, and which at the same time inhibits carbonization of the residues and formation of deposits on hot reactor walls. These and other objects are achieved by heating the residue in a pressurized reactor by passage of an alternating electric current.
The invention thus provides a process for producing alkylchlorosilanes from the residues from the direct synthesis of alkylchlorosilanes, which comprise liquid constituents with a boiling point of at least 70° C. at 1013 hPa and further constituents, including metals and compounds thereof, in which the reaction mixture is heated in a pressurized reactor to a reaction temperature of from 200 to 500° C. via passage of alternating current.
The process uses residues from the direct synthesis of alkylchlorosilanes to provide useful monosilanes. It is preferable here that relatively high-molecular-weight constituents of the residues are cleaved to give monosilanes. The process preferably requires no use of catalysts and no use of further starting materials. Deposits of solids on the reactor walls are very substantially avoided.
Methylchlorosilanes of the general formula MeaHbSiCl4-a-b are preferably produced, in which Me is a methyl moiety, a is 1, 2, or 3, and b is 0 or 1.
The residues from the direct synthesis consist in essence of volatile constituents with a boiling point of at least 70° C., in particular at least 100° C., at 1013 hPa, and metals or compounds of these, in dissolved or finely suspended form. In particular, the residues comprise metals from the group of Al, Cu, Zn, Sn, Fe, Ti, and/or compounds of these. The residues can also comprise further solids, e.g. silicon and carbon black. The residue mostly comprises disilanes.
The residues are introduced batchwise or continuously into a pressurized reactor and heated to the temperature required for reaction via passage of alternating current.
The reactor is preferably operated at at least 250° C. and with preference at at most 350° C.
The pressure is preferably at least 20 bar, more preferably at least 30 bar, and preferably at most 100 bar, in particular at most 80 bar.
The reaction product is preferably condensed, and if appropriate freed from solids, and can be returned to the alkylchlorosilane mixture produced in the direct synthesis process, or else can be separately isolated to give pure substances.
Unless otherwise stated, all of the amounts and percentages stated are based on weight. Me means a methyl moiety.
A high-boiling-point residue from the direct synthesis of methylchlorosilanes was used and according to GC was composed of:
- 54% of disilanes (mixture of 1,1,1,2,2,2-hexamethyl-disilane, 1-chloropentamethyldisilane, 1,1-dichloro-tetramethyldisilane, 1,2-dichlorotetramethyldisilane, 1,1,2-trichlorotrimethyldisilane, and 1,1,2,2-tetra-chlorodimethyldisilane),
- 9% of trisilanes of the general formula
- ClaMe3-aSi(ClbMe2-b)SiSiClcMe3-c, where each of a and c is from 0 to 3, and b is from 0 to 2,
- 7% of silamethylenes (carbosilanes) of the general formula ClaMe3-aSiCH2SiMe3-bClb, where each of a and b is from 0 to 3,
- 2% of metals and metal compounds (in particular Al, Zn, Sn, Fe, Ti),
- 2% of alkylchlorosilanes, and also
- 26% of unidentified compounds, each at low concentration.
The high-boiling-point residue was fed in liquid form into an autoclave of volume 0.92 1. The reaction mixture was heated to 270° C. via passage of alternating current and kept at this temperature for 180 min.
The autoclave was cooled to ambient temperature. The product mixture was removed and analyzed by GC:
- 51.7% of methylchlorosilanes, of which
- 40.4% of dichlorodimethylsilane,
- 7.2% of trichloromethylsilane,
- 2.5% of chlorotrimethylsilane,
- 1.4% of dichloromethylsilane,
- 0.5% of uncleaved disilanes,
- 6.8% of silamethylenes,
- 41% of unidentified compounds.
There was only very little solid deposited on the wall of the reactor and on the base of the reactor. The solid was in the form of fine particulates and could easily be removed mechanically.
Claims (10)
1. A process for producing alkylchlorosilanes from a reaction mixture comprising residues from the direct synthesis of alkylchlorosilanes which comprise liquids with a boiling point of at least 70° C. at 1013 hPa and further constituents comprising metals and metal compounds, comprising heating the reaction mixture in a pressurized reactor to a reaction temperature of from 200 to 500° C. via passage of alternating electrical current through the liquid reaction mixture.
2. The process of claim 1 , wherein further constituents in the reaction mixture comprises metal compounds.
3. The process of claim 1 , wherein methylchlorosilanes of the formula MeaHbSiCl4-a-b are produced, in which Me is a methyl moiety, a is 1, 2, or 3, and b is 0 or 1.
4. The process of claim 1 , in which disilanes are present in the residue.
5. The process of claim 1 , in which no further starting materials or catalysts are added.
6. The process of claim 1 , which is conducted at a pressure of from 20 to 100 bar.
7. The process of claim 1 , wherein no HCl and no H2 are added.
8. The process of claim 1 , which takes place at a temperature of from 250° C. to 350° C. and at a pressure of from 30 bar to 80 bar.
9. The process of claim 1 , further comprising removing a product from the reactor and isolating a pure monosilane from the product.
10. The process of claim 1 , further comprising separating a product from the reactor, and adding at least a portion thereof to alkylchlorosilanes produced in a direct synthesis reaction.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102008000410 | 2008-02-26 | ||
DE102008000410A DE102008000410A1 (en) | 2008-02-26 | 2008-02-26 | Process for the preparation of alkylchlorosilanes from the residues of the direct synthesis of alkylchlorosilanes |
DE102008000410.3 | 2008-02-26 | ||
PCT/EP2009/051771 WO2009106447A1 (en) | 2008-02-26 | 2009-02-16 | Method for producing alkyl chlorosilanes from the residues of the direct synthesis of alkyl chlorosilanes |
Publications (2)
Publication Number | Publication Date |
---|---|
US20110009659A1 US20110009659A1 (en) | 2011-01-13 |
US8207366B2 true US8207366B2 (en) | 2012-06-26 |
Family
ID=40552062
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/865,664 Expired - Fee Related US8207366B2 (en) | 2008-02-26 | 2009-02-16 | Method for producing alkyl chlorosilanes from the residues of the direct synthesis of alkyl chlorosilanes |
Country Status (8)
Country | Link |
---|---|
US (1) | US8207366B2 (en) |
EP (1) | EP2245036B1 (en) |
JP (1) | JP2011513265A (en) |
KR (1) | KR20100098725A (en) |
CN (1) | CN101959895A (en) |
AT (1) | ATE525380T1 (en) |
DE (1) | DE102008000410A1 (en) |
WO (1) | WO2009106447A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102006053157A1 (en) * | 2006-11-10 | 2008-05-15 | Wacker Chemie Ag | Method for vaporizing constituents of a liquid |
WO2013082548A1 (en) | 2011-11-30 | 2013-06-06 | Sarepta Therapeutics, Inc. | Oligonucleotides for treating expanded repeat diseases |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2598435A (en) | 1949-08-18 | 1952-05-27 | Gen Electric | Process for treating organoplysilanes |
US2681355A (en) | 1953-02-20 | 1954-06-15 | Dow Corning | Method of preparing organosilanes |
DE19711693A1 (en) | 1997-03-20 | 1998-09-24 | Wacker Chemie Gmbh | Process for the preparation of alkylchlorosilanes from the residues of the direct synthesis of alkylchlorosilanes |
DE10039172C1 (en) | 2000-08-10 | 2001-09-13 | Wacker Chemie Gmbh | Production of alkylchlorosilanes, useful in production of silicone, e.g. polydimethylsiloxane or silicone resin, from high-boiling liquid residue from direct alkylchlorosilane synthesis involves heating with hydrogen chloride and silicon |
EP1505070A1 (en) | 2003-08-05 | 2005-02-09 | GE Bayer Silicones GmbH & Co. KG | Process for preparing chlorosilanes |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10354262A1 (en) * | 2003-11-20 | 2005-06-23 | Wacker-Chemie Gmbh | Process for the preparation of alkylchlorosilanes from the residues of the direct synthesis of alkylchlorosilanes |
-
2008
- 2008-02-26 DE DE102008000410A patent/DE102008000410A1/en not_active Withdrawn
-
2009
- 2009-02-16 AT AT09715627T patent/ATE525380T1/en active
- 2009-02-16 WO PCT/EP2009/051771 patent/WO2009106447A1/en active Application Filing
- 2009-02-16 KR KR1020107017254A patent/KR20100098725A/en active IP Right Grant
- 2009-02-16 US US12/865,664 patent/US8207366B2/en not_active Expired - Fee Related
- 2009-02-16 CN CN2009801063471A patent/CN101959895A/en active Pending
- 2009-02-16 JP JP2010548072A patent/JP2011513265A/en not_active Withdrawn
- 2009-02-16 EP EP09715627A patent/EP2245036B1/en not_active Not-in-force
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2598435A (en) | 1949-08-18 | 1952-05-27 | Gen Electric | Process for treating organoplysilanes |
US2681355A (en) | 1953-02-20 | 1954-06-15 | Dow Corning | Method of preparing organosilanes |
DE19711693A1 (en) | 1997-03-20 | 1998-09-24 | Wacker Chemie Gmbh | Process for the preparation of alkylchlorosilanes from the residues of the direct synthesis of alkylchlorosilanes |
US5877337A (en) | 1997-03-20 | 1999-03-02 | Wacker-Chemie Gmbh | Process for preparing alkylchlorosilanes from the residues of direct synthesis of alkylchlorosilanes |
DE10039172C1 (en) | 2000-08-10 | 2001-09-13 | Wacker Chemie Gmbh | Production of alkylchlorosilanes, useful in production of silicone, e.g. polydimethylsiloxane or silicone resin, from high-boiling liquid residue from direct alkylchlorosilane synthesis involves heating with hydrogen chloride and silicon |
US6344578B1 (en) | 2000-08-10 | 2002-02-05 | Wacker-Chemie Gmbh | Process for working up residues from the direct synthesis of organochlorosilanes |
EP1505070A1 (en) | 2003-08-05 | 2005-02-09 | GE Bayer Silicones GmbH & Co. KG | Process for preparing chlorosilanes |
US20050113592A1 (en) | 2003-08-05 | 2005-05-26 | Ge Bayer Silicones Gmbh & Co. | Method for preparing chlorosilane |
Also Published As
Publication number | Publication date |
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US20110009659A1 (en) | 2011-01-13 |
ATE525380T1 (en) | 2011-10-15 |
EP2245036B1 (en) | 2011-09-21 |
CN101959895A (en) | 2011-01-26 |
JP2011513265A (en) | 2011-04-28 |
DE102008000410A1 (en) | 2009-08-27 |
EP2245036A1 (en) | 2010-11-03 |
WO2009106447A1 (en) | 2009-09-03 |
KR20100098725A (en) | 2010-09-08 |
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Owner name: WACKER CHEMIE AG, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BOECK, MANFRED;FUCHS, PAUL;MAUTNER, KONRAD;REEL/FRAME:024798/0381 Effective date: 20100701 |
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